Two small Spanish ships, commanded by Bartolomé Ruiz, sail southwards in the Pacific in 1527 towards Peru. Their journey brings them across the equator (they are the first Europeans to cross the line in this ocean). The Spaniards are surprised to come across an ocean-going raft, made of balsa wood and fitted with cotton sails, with a crew of twenty.

When they seize the raft, its rich contents also astonish them (the ornaments and textiles are described later in Glowing terms to the Spanish king). The people who sent out this trading vessel are clearly worth meeting. Ruiz takes the precaution of keeping three of the crew to be trained as interpreters.

This chance encounter is the first contact between Europeans and the fabulously wealthy empire of the Incas. And the glimpse of Inca treasure can only inflame Spanish greed.

The leader of the expedition (not aboard on the reconnaissance by Ruiz) is Francisco Pizarro. The winter of 1527 is spent on a swampy uninhabited island. The conditions are so appalling that by the spring Pizarro is left with only thirteen companions. They sail on southwards. At Tumbes they reach their first Inca city. Two of Pizarro's men go ashore. Their reports confirm that this is indeed a rich and civilized society.

It takes Pizarro eighteen months, mainly spent at the royal court in Spain, to drum up sufficient support for a voyage of conquest. The great Cortes happens to be at the Spanish court at the same time. He offers personal encouragement, and the example of his own astonishing achievement in Mexico inspires ambitious young Spaniards to join the new cause.

Ennobled, and granted the status of governor of a notional Spanish province along the Peruvian coast, Pizarro leaves Spain with a small fleet in January 1530. At the end of the year, in December, his expedition sails south from Panama.

Unlike the speedy advance of Cortes into Mexico in 1519, Pizarro's progress south is slow. For some reason he chooses to march his men along much of the difficult coast of Ecuador, causing great hardship and delay. Nearly two years have passed by the time he establishes a small Spanish settlement, which he calls San Miguel, near Piura in the coastal plain of northern Peru.

From here, at last, in September 1532, he marches out to attack the vast empire of the Incas. His army by now consists of 62 horsemen and 106 foot soldiers.

Atahualpa: 1532

As the Spaniards march into the Inca empire, in 1532, they are helped by two fortunate circumstances. One is that the empire is in a state of turmoil caused by civil war between two brothers, sons of an Inca ruler who has died about five years previously. Victory has recently gone to Atahualpa, the brother who controls the northern half of the empire. But there is still much support around the Inca capital, Cuzco, for his rival. In these circumstances the advance of the small band of strangers is dealt with less forcefully than might otherwise have been the case.

The other piece of good fortune is that Atahualpa is encamped in the north, at Cajamarca, nor far from the Spaniards' starting point.

After climbing into the Andes to a height of about 13,500 feet, Pizarro and his small party of conquistadors enter the valley of Cajamarca in November. Atahualpa's army is encamped in bright tents beyond the city. The splendour of the site both Impresses and alarms the intruders. But there is nowhere to go but forward. They enter the town of Cajamarca, unopposed, and then send a small party forward to present themselves to the Inca.

Without dismounting, they ride into the courtyard where he is relaxing with his women. This is like parking one's tanks on someone's lawn, for horses - together with guns - are the Spaniards' main strength.

Atahualpa at first shows little reaction, except perhaps disdain. But the horses interest him. They are the first that he or his companions have seen. The Spaniards accept from the women the local drink, chicha (with some hesitation, for fear of poison). Then one of the conquistadors gives an equestrian display on a particularly lively horse.

Atahualpa agrees to visit Pizarro in Cajamarca the following day.

The massacre of Cajamarca: 1532

The Spaniards, aware of their extreme vulnerability, are uncertain how to receive the Inca. They take the precaution of concealing their limited forces - cavalry, infantry, artillery - in the arcades around the square. A prearranged signal to attack will be used only if the situation demands it.

When Atahualpa enters Cajamarca, on a magnificent litter carried high by his nobles, the square appears to be empty. With only a narrow entrance, the space fills up slowly with his followers, lightly armed. Then a single Spaniard walks towards the Inca - Pizarro's priest.

The priest solemnly begins explaining to Atahualpa the truth of the Christian religion (a requirement in the Spanish empire, when confronting pagan people, if there is a danger of bloodshed). Atahualpa demands to see the prayer book which the priest is holding. He leafs through it, then flings it to the ground.

The outraged priest turns back, shouting for vengeance. Pizarro gives the prearranged signal for the ambush.

The din of terrifying artillery and gunfire, the onslaught of unfamiliar cavalry and the ferocity of Spaniards in mortal danger, all combine to throw the Indians into desperate panic. Trapped by the narrow entrance to the square, they are defenceless targets for butchery. Reports state that the killing lasts two hours. The Indian dead are numbered in thousands rather than hundreds, with the Spanish horsemen carrying the carnage into the streets and open spaces outside the square.

The only wound suffered by any Spaniard that day is a deep cut on Pizarro's hand, received when he defends Atahualpa from a sword blow. He needs the Inca alive.

Pizarro and Atahualpa: 1532

Pizarro is well aware of how Cortes controlled Mexico through a captive ruler. He now sets about doing the same in Peru, having repeated the almost impossible feat of getting the emperor into his power (there is evidence that Atahualpa had the same intention that afternoon, expecting to use his vastly greater number of men to seize Pizarro and his followers). Like Cortes, he ensures that the emperor is treated with every respect - essential if his subjects are still to revere him and obey his orders.

But Pizarro makes a bargain beyond anything Cortes had dreamed of. The Inca offers a ransom for his freedom - a room of gold and silver, which becomes one of the enduring images of the Spanish conquest.

The room of gold: 1532-1533

The room proposed for the emperor's ransom measures 22 feet by 18 feet, and is about 15 feet high. It is to be filled, within two months, to half its height in gold; during the same period the entire room will be filled twice over with silver.

The filling of the room provides Pizarro with a welcome breathing space, as the precious metals are stripped from palaces and temples all over the Inca empire and are brought to Cajamarca on caravans of llamas. Pizarro needs time for Spanish reinforcements to enlarge his tiny army. They arrive in April 1533, under Diego de Almagro, roughly doubling Pizarro's strength.

In March 1533 Pizarro gives orders for the hoard of precious metals to be melted down. Nine furnaces are kept at work for three months. More than eleven tons of gold and twice as much silver, much of it in the form of artefacts of great beauty, are fed into these voracious cauldrons of Spanish greed.

The king's share (one fifth) goes off to him in Spain, and Pizarro's brave conquistadors now receive their reward - 90 pounds of gold and 180 pounds of silver for each horseman, half that amount for every foot soldier.

The room of gold and silver has been filled and emptied, but Atahualpa is still a prisoner. The Spaniards, probably never intending to keep their word, are uncertain what do with him. A rumour grows that he has given orders for a great army to advance from the south to rescue him. It is false, but it provides an excuse for his very expedient death.

In July 1533 Atahualpa is accused of treason, is rapidly convicted, and is tied to a stake at the centre of the square in Cajamarca where his followers were massacred. He is sentenced to death by burning. The priest persuades him at the last moment to accept Christianity, so he is granted the mercy of being garrotted.

Peru of the conquistadors: 1533 - 1548

Peru has been conquered with greater violence, and in a more buccaneering spirit, than other parts of the developing Spanish empire. The province retains this character - as is well suggested by the fate of the leading families in the conquest.

Pizarro's colleague, Diego de Almagro, rebels and is executed in 1538. Supporters of Almagro's son assassinate Pizarro himself in 1541. Almagro's son is executed in 1542. Pizarro's brother Gonzalo kills a viceroy, newly arrived from Spain, in 1544 and is himself executed in 1548. Meanwhile the Inca nobility remains a permanent danger. As late as 1780 an Indian rebellion is led by a descendant of the Inca dynasty, who takes an ancestral name - Tupac Amaru.

Yet Peru is also a province of immense wealth and importance in the Spanish empire - a fact acknowledged in the second half of the 16th-century, when the viceroyalty of Peru adminsters the whole of Spanish south America except Venezuela.

Peru's contribution to the wealth of the empire began with an astonishing roomful of precious metal. This abundance continues, indeed is much increased. The Inca gold and silver came entirely from surface sources, found as nuggets or panned from river beds. They had no mines. The Spaniards soon discover mines to produce massive wealth - particularly, from 1545, the silver mines at Potosí.

Spanish silver: 16th century

The wealth of Spain's new colonies in Latin America derives mainly from silver. In 1545 a prodigious source of the metal is discovered at Potosí, in modern Bolivia. This region, high in the Andes, is so rich in both silver and tin that it eventually has as many as 5000 working mines.

In 1546, a year after the discovery at Potosí, silver is found at Zacatecas in Mexico. Other major new sources of the metal are found in Mexico in the next few years. At the same time sources of gold are being tapped, though in much less quantity.

Convoys of Spanish caravels, after delivering to Portobelo the European goods needed in the colonies, carry back to Spain the precious bullion with which the colonists pay for it - together with the 20% of all gold and silver due to the Spanish crown.

These treasures attract privateers from northern Europe - meaning privately owned vessels operating, even if informally, on behalf of a government. Their captains are drawn to the Spanish Main (the mainland of Spanish America, where the ships dock) like wasps to a honey pot. Sailors from England, such as Francis Drake, prey on the Spanish fleets in what is effectively a programme of national piracy.

At the Spanish end, all trade has to be channelled through the official Casa de Contratación (House of Trade) established in Seville in 1503. This monopoly brings great wealth to Seville, and an increase in prosperity from this flow of bullion spreads outwards through Europe. The region of Seville, and indeed the whole of Spain, cannot provide all the goods required by the colonists. Raw materials and manufactured goods from far flung regions make their way to Seville for transport to America.

Europe in the 16th century is already experiencing, for other reasons, an inflationary pressure. The Spanish bullion has an added effect in pushing prices up.